Terminal won't accept my password

I have tried time and again to edit files through Terminal but when prompted for my password it will not accept my password(won't type it) I use an iMac 10.8. Does anyone know anything that could help me?

Yes!
That's correct. The terminal does NOT ever show the characters in your password as you type it, and no indication that you are typing anything (remains blank)
It's a security tactic, so just type in your password, and press enter. It will then continue with whatever command you are using.

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